CFD Online Logo CFD Online URL
Home > Forums > FLUENT

Different Drag coefficient

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   April 28, 2013, 07:26
Question Different Drag coefficient
New Member
Join Date: Nov 2012
Posts: 6
Rep Power: 7
babak.mahjoub is on a distinguished road
Hi everybody.

I am trying to study the flow over a circular cylinder.

Simply put, the problem is I get different drag coefficient (and other coefficients as well) with the same Reynolds number,

Of course each time I change the diameter and velocity, but the Reynolds number remains the same, I though it is supposed to get me the same result.

For instance:

Fluid is air at 20 Celsius, transient flow, 2d, laminar

D= 0.16 u= 0.0095 => Re=100 Drag co. = 0.2323
D= 0.016 u= 0.095 => Re=100 Drag co. = 0.0183
While I find in literatures that this value must be around 1.2

If Reynolds number is not the only determinant factor, how do I validate my data with privious studies, as they just mentiones Reynolds number, not the inlet velocity


Last edited by babak.mahjoub; April 29, 2013 at 09:53.
babak.mahjoub is offline   Reply With Quote

Old   April 29, 2013, 07:34
Senior Member
RodriguezFatz's Avatar
Join Date: Jun 2011
Location: Germany
Posts: 1,297
Rep Power: 20
RodriguezFatz will become famous soon enough
From what I learned from previous threads here, it could be that your domain is too small, i.e. the distance from inlet to cylinder is too small or the distance from cylinder to outlet. Can you post a picture of your domain?
The skeleton ran out of shampoo in the shower.
RodriguezFatz is offline   Reply With Quote


circular cylinder, drag coefficients, reynolds number

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
problem with saving drag coefficient colopolo FLUENT 5 April 12, 2013 10:59
Calculation of Drag Coefficient, Help Please teek22 CFX 1 April 26, 2012 18:41
Drag Coefficient Convergence Problem John FLUENT 16 September 4, 2009 02:44
Drag coefficient for parcels in dieselFoam sebastian_vogl OpenFOAM Running, Solving & CFD 5 December 31, 2008 13:19
Automotive test case vinz OpenFOAM Running, Solving & CFD 98 October 27, 2008 09:43

All times are GMT -4. The time now is 12:10.